• Transactions of the Korean Society of Mechanical Engineers B
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• 제35권10호
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• pp.1105-1110
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• 2011

Flow-accelerated corrosion (FAC) is a well-known phenomenon that may occur in piping and components. Most nuclear power plants have carbon-steel-pipe wall-thinning management programs in place to control FAC. However, various other erosion mechanisms may also occur in carbon-steel piping. The most common forms of erosion encountered (cavitation, flashing, Liquid Droplet Impingement Erosion (LDIE), and Solid Particle Erosion (SPE)), have caused wall thinning, leaks, and ruptures, and have resulted in unplanned shutdowns in utilities. In particular, the damage caused by LDIE is difficult to predict, and there has been no effort to protect piping from erosive damage. This paper presents an evaluation method for LDIE. It also includes the calculation results from prediction models, a review of the experimental results, and a comparison between the UT data in the damaged components and the results of the calculations and experiments.

• Corrosion Science and Technology
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• 제19권3호
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• pp.131-137
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• 2020

A number of piping components in the secondary system of nuclear power plants (NPPs) are exposed to aging mechanisms, such as flow-accelerated corrosion (FAC), cavitation, flashing, solid particle erosion, and liquid droplet impingement erosion. Those mechanisms may lead to thinning, leaking, or rupture of the components. Due to the pipe ruptures caused by wall thinning in Surry unit 2 in the USA in 1986 and Mihama unit 3 in Japan in 1994, pipe wall thinning management has emerged as one of the most important issues in the nuclear industry. To manage pipe wall thinning, a foreign program has been utilized for NPPs in Korea since 1996. As our experience and knowledge of pipe wall thinning management have accumulated, our program needs to reflect our experience, requests from users, and the result of recent experiments using Flow Accelerated Corrosion Testing System (FACTS). FACTS is the empirical experimental facility developed by Korea Atomic Energy Research Institute (KAERI) for tests. Accordingly, KEPCO-E&C developed a 3D-based pipe wall thinning management program called ToSPACE in 2016. This paper describes a comparison between the FAC analysis results using ToSPACE and the experimental results using FACTS to verify their applicability to pipe wall thinning management in NPPs.

• Journal of the Korean Society of Safety
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• 제26권4호
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• pp.34-40
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• 2011

This paper is purposed to develop an leakage current detecting system(LCDS) which can prevent electrical fires on breaker capacity expansion as well as ruptures of XL(Extra long) pipelines and power failure by operation of ELB(Earth leakage breaker) at auto water machine in winter. In order to develop LCDS, this paper studied field state investigation, field state experiment, development of leakage alarm system and verification experiments. Field states investigation at livestock companies(10 companies) in cheong-won location to deduce the problems of auto water machine is analyzed. The field state experiment is conducted at B livestock company in cheong won location. The field state experiment method is measured with leakage current when ELB tripped by environment factor(fine, cloudy, and rainy day). The LCDS is developed as MCU(Micro Control Unit) part applied leakage current values at B livestock company. Verification experiments for the leakage current detecting system were conducted by two methods of current supply and field test. Results show that LCDS suggested in this paper are valuable and usable in auto water machine based on environment factor, which will prevent severe damage to human beings and properties and reduce the electrical fires in livestock.

• Journal of Chest Surgery
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• 제29권11호
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• pp.1257-1262
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• 1996

From January 1989 to February 1996, 50 patients with a traumatic diaphragmatic rupture were treated at the Yonsei University Wonju College of Medicine. There were 40 male and 10 female patients. The ages ranged from 2 to 80 years, with peak incidence in third decades. Thirty-nine cases had blunt trauma (traffic accident 29, falls down 7, others 3), and 11 cases had penetrating injuries (stab injury 9, gun shot 1, broken glass 1). The most common symptoms were dyspnea (76%), chest pain (58%), and abdominal pain (52%). In blunt trauma, the rupture was located in the left in 30 cases, right in 9 cases and in penetrating trauma, the rupture was located in the left in 8 cases and in the right in 3 cases. Eighteen cases underwent thoracotomy alone, 29 cases underwent laparotomy only and 3 cases had combined thoracotomy and laparotomy. The postoperative mortality occurred in 6% (3 cases), and the cause of death were septic shock (1), intracranial hemorrhage (1), and respiratory failure (1).

• Journal of the Korean Society for Nondestructive Testing
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• 제22권1호
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• pp.32-37
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• 2002

The presence of hydrogen in industrial plants is a source of damage. Hydrogen attack is one such form of degradation and often causing large tube ruptures that necessitate an immediate shutdown. Hydrogen attack may reduce the fracture toughness as well as the strength of steels. This reduction is caused partially by the presence of cavities and microcracks at the grain boundaries. In the past several techniques have been used with limited results. This paper describes the application of an ultrasonic velocity and attenuation in hydrogen damage. Ultrasonic tests showed a decrease in wave velocity and an increase in attenuation. Such results demonstrate the potential for ultrasonic nondestructive testing to quantify damage. Based on this study, reliable recommendation is suggested to detect hydrogen attack.

• Geosciences Journal
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• 제22권6호
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• pp.871-880
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• 2018

During and shortly after the 2017 Pohang Earthquake ($M_w$ 5.4), sand blows were observed around the epicenter for the first time since the beginning of instrumental seismic recording in South Korea. We carried out field surveys plus satellite and drone imagery analyses, resulting in observation of approximately 600 sand blows on Quaternary sediment cover in this area. Most were observed within 3 km of the epicenter, with the farthest being 15 km away. In order to investigate the ground's susceptibility to liquefaction, we conducted a trench study of a 30 m-long sand blow in a rice field 1 km from the earthquake epicenter. The physical characteristics of the liquified sediments (grain size, impermeable barriers, saturation, and low overburden pressure) closely matched the optimum ground conditions for liquefaction. Additionally, we found a series of soft sediment deformation structures (SSDSs) within the trench walls, such as load structures and water-escaped structures. The latter were vertically connected to sand blows on the surface, reflecting seismogenic liquefaction involving subsurface deformation during sand blow formation. This genetic linkage suggests that SSDS research would be useful for identifying prehistoric damage-inducing earthquakes ($M_w$ > 5.0) in South Korea because SSDSs have a lower formation threshold and higher preservational potential than geomorphic markers formed by surface ruptures. Thus, future combined studies of Quaternary surface faults and SSDSs are required to provide reliable paleoseismological information in Korea.

• Clinical and Experimental Reproductive Medicine
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• 제48권3호
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• pp.221-228
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• 2021

Objective: This study investigated the effect of crocin in methylglyoxal (MGO)-induced diabetic male mice. Methods: Seventy 1-month-old male NMRI mice weighing 20-25 g were divided into seven groups (n=10): sham, MGO (600 mg/kg/day), MGO+crocin (15, 30, and 60 mg/kg/day), MGO+metformin (150 mg/kg/day), and crocin (60 mg/kg/day). MGO was administered orally for 30 days. Starting on day 14, after confirming hyperglycemia, metformin and crocin were administered orally. On day 31, plasma and tissue samples were prepared for experimental assessments. Results: Blood glucose and insulin levels in the MGO group were higher than those in the sham group (p<0.001), and decreased in response to metformin (p<0.001) and crocin treatment (not at all doses). Testis width and volume decreased in the MGO mice and improved in the crocin-treated mice (p<0.05), but not in the metformin group. Superoxide dismutase levels decreased in diabetic mice (p<0.05) and malondialdehyde levels increased (p<0.001). Crocin and metformin improved malondialdehyde and superoxide dismutase. Testosterone (p<0.001) and sperm count (p<0.05) decreased in the diabetic mice, and treatment with metformin and crocin recovered these variables. Luteinizing hormone levels increased in diabetic mice (p<0.001) and crocin treatment (but not metformin) attenuated this increase. Seminiferous diameter and height decreased in the diabetic mice and increased in the treatment groups. Vacuoles and ruptures were seen in diabetic testicular tissue, and crocin improved testicular morphology (p<0.01). Conclusion: MGO increased oxidative stress, reduced sex hormones, and induced histological problems in male reproductive organs. Crocin and metformin improved the reproductive damage caused by MGO-induced diabetes.

• Journal of the Korean Orthopaedic Association
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• 제53권6호
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• pp.547-551
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• 2018

Three Stener-like lesions of the metacarpophalangeal joint of the fingers and a rupture of the first dorsal interosseous muscle mimicking the lesion in the index finger were observed. Two cases in the little fingers had a true Stener's lesion. In one case in the index finger, the ruptured ligament was retracted and located under the intact sagittal band, which was also observed by preoperative magnetic resonance imaging (MRI). Rupture of the first dorsal interosseous muscle was misdiagnosed preoperatively as a Stener's lesion in the index finger by ultrasonography. MRI should be an essential differential diagnostic exam for collateral ligament ruptures of the metacarpophalangeal joint of the fingers.

• Clinics in Shoulder and Elbow
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• 제21권4호
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• pp.213-219
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• 2018

Background: The study of conservative and surgical treatment of distal biceps tendinopathy and associated biceps tendon partial rupture. Methods: Twenty-one cases with distal biceps tendonitis and partial ruptures were studied who visited Pohang Semyeong Christianity Hospital from June 2010 to August 2017. The mean age was 57.1 years (39-69 years), 14 males and 7 females. The mean duration of symptom at the time of first visit was 4.9 months (0.2-14 months). Ultrasonography and magnetic resonance imaging were performed for patients with severe symptoms. According to the severity of the symptoms, splint immobilization, oral nonsteroidal anti-inflammatory drugs, and ultrasound-guided steroid injection were performed. Surgical treatment was performed if the patient did not respond to conservative treatment for 3 to 6 months or longer. Results: There were 9 cases of partial rupture of the distal biceps tendon associated with distal biceps tendinopathy on imaging studies. Conservative treatment showed symptomatic improvement in 16 of 21 cases. In 4 cases with a relatively mild symptom, anti-inflammatory analgesics and intermittent splinting showed good result. In 12 cases, symptoms improved after ultrasonography-guided steroid injection. Surgical treatment was performed on 5 cases that did not respond to conservative treatment. Conclusions: Conservative treatment of distal biceps tendinopathy may promise good results. However, in case of partial tear of the distal biceps tendon and refractory to conservative treatment, surgical treatment may be needed.

• Steel and Composite Structures
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• 제43권6호
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• pp.735-757
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• 2022

The behavior of shear deficient under-balanced reinforced concrete beams with rectangular cross-sections, which were externally strengthened with CFRP composite along shear spans, was experimentally investigated under vertical load. One of the specimens represents a reference beam without CFRP strengthening and the other specimens have different width/strip spacing ratios (w_f/s_f). The optimum strip in terms of w_f/s_f, which will bring the beam behavior to the ideal level in terms of strength and ductility, was determined according to the regulations. When the w_f/s_f ratio exceeds 0.55, the behavior of the beam shifted from shear failure to bending failure. However, it has been observed that the w_f/s_f ratio should be increased up to 0.82 in order for the beam to reach sufficient shear reserve value according to the codes. It is also observed that the direction and weight of the CFRP composite are one of the most critical factors and 240 gr/m² CFRP strips experienced sudden ruptures in the shear span after the cracking of the concrete. It is considered as a deficiency that the empirical shear capacity formulas given for the beams reinforced with CFRP in the regulations do not take into account both direction and weight of CFRP composites.